With Republicans confident of reclaiming control of the Senate, Democrats are looking to black voters in two Southern states to help preserve their majority. Republicans, who are expected to keep control of the House in Tuesday’s election and need to gain six seats to win a majority in the Senate, have been bolstered by President Barack Obama’s low popularity ratings. But the president remains an inspirational figure for many African-Americans, and Democrats are pushing hard for high turnout among their core constituencies, including women and minorities....